Muffler



sem. 1o, 1935. L. R. HEATH 2,013,956.

MUFFLER Filed NOV. 16, 1931 5 Sheets-Sheet 1 abbr/nu, o.

Sept. 10, 1935.

MUFFLER Filed Nov. 16, 1931 3 Sheets-Sheet 2 l m n wm :www

L. R. HEATH Sept. l0, 1935.

MUFFLER Filed Nov. 16, 1951l s sheets-sheet 5 31a/012Mo@ Hed/Zh @M01/nuja.

Patented Sept. l0, 1935 UNITED STATES PATENT OFFICE 8 Claims.

The invention relates to improvements in mufflers and more particularly to those adapted for use with internal combustion engines.

The principal object of the invention is to provide a muffler which may be easily and inexpensively manufactured and which Will eifectively diffuse the gas quietly and without back pressure. The arrangement is such that the flow of gas is not interrupted by eddy currents and the characteristic pulsating exhaust of the internal combustion engine, is greatly reduced, both by cooling and the application of well known aerodynamical principles.

A further object of the invention is to provide a construction which' may if desired, be employed within an enveloping jacket, in which part of the gases after being influenced by the interior construction of the muffler, are collected and from which they are either discharged into the air by their expanding force, aided in escaping by the dynamic reaction of the air flow around the casing, orlwithdrawn back into the central conduit of the muffler before being discharged. The enveloping jacket is to be provided in forms which best adapt themselves to conditions and requirements of any particular engine installation, whether automotive, aeronautical or stationary.

With the foregoing in view, the invention resides in the novel subject matter hereinafter described and claimed, description being accomplished by reference to the accompanying drawings.

Fig. 1 is a central longitudinal sectional view through a portion of a mufller constructed in accordance with the invention.

Fig. 2 is a transverse sectional view on line 2-2 of Fig. 1.

Fig. 3 is a fragmentary longitudinal sectional view showing a different form of construction.

Fig. 4 is a fragmentary longitudinal section showing a still further form o construction.

Fig. 5 is a longitudinal section illustrating a substantially flat construction whereas the other forms are of annular cross section.

Fig. 6 is a transverse sectional view on line 6-6 of Fig. 5.

Fig. '7 is a fragmentary longitudinal section showing yet another form of construction.`

Fig. 8 is a longitudinal sectional view of a complete tapered muiiler constructed in a manner very similar to that shown in Fig. 1.

Fig. l2 is a longitudinal sectional view partly in elevation showing a two-stage mufiler.

Figs. 13 and A14 are elevations partly in section showing two forms of mulers well suited for aircraft.

Fig. l5 is atransverse section on line l5--I 5 of Fig. 14.

Fignl is a longitudinal sectional view partly in elevation illustrating yet another form of construction.

In the form of construction shown in Figs. 1- and 2, a gas conduit is provided having a plurality of longitudinally spaced axially alined cylindrlcal portions 2| which enlarge the conduit both externally and internally, said conduit also having a plurality of longitudinally spaced axially alined Venturi-like portions which decrease the diameter of the conduit both internally and externally between the enlargements. Tubular means, in the form of a sleeve 23, snugly surrounds the cylindrical portions 2| and co-acts with the exteriors of the Venturi-like portions 20v in providing annular pockets 24. Substantially at their smallest diameters, these Venturi-like portions are provided with auxiliary portage from their interiors into the pockets 24, and the sleeve 23 is formed with auxiliary openings 26 extending from said pockets 24 to its exterior.

In order to maintain low back-pressure, the passage through the Venturi-like portions of the conduit should be streamlined as much as possible and the throats should not be unduly restricted. Well proportioned Venturi-like tubes will not-materially retard the flow of a. gas through them, although the gas velocity is increased and the pressure decreased at the tubes smallest diameter.

This characteristic reaction is used with great eiectiveness in the present mulller, especially during the passage of the high-pressure part of the pulsating exhaust gas discharge. As the pulsating exhaust gases pass through the first several Venturi-like portions 20 of the conduit, part of the gas from each succeeding high-pressure wave peak, expands and escapes under reduced pressure in the direction of the arrows and is diffused by passing through auxiliary ports 25, pockets 24 and openings 26 into the atmosphere. The high pressure wave peaks, at this stage, are of too great an intensity to be entirely neutralized by the Venturi tubes reaction. The result is that part of each high-pressure wave-is discharged through the auxiliary ports and openings at a lessened pressure, hence less noislly. Should there be a suflicient number of Venturi-like` formations, the high-pressure wave peak will be materially resaid Venturi tubes.

duced by dissipation and cold air will be drawn substantially continuously into the conduit through the last few auxiliary ports and openings provided. It is also conceivable that during the passage of the low-pressure part of the wave through the Venturi-like formations, air may be drawn through the auxiliary openings into the conduit.

The operation as described serves to effectively smooth out the exhaust pulsations within the conduit without excessive back-pressure.

Insofar as the specific structure of the conduit of Figs. 1 and 2 is concerned, it preferably consists of a plurality of separate Venturi tubes upon which the numbers 20 have been placed, and spacing tubes between and abutting the ends of The intermediate portions of the Venturi tubes form the restrictions 22 and the ends of said Venturi tubes and the spacing tubes form the swells 2|.

In the form of construction shown in Fig. 3, a plurality of longitudinally spaced axially alined cylindrical conduit portions 28 are provided, and a plurality of Venturi-like conduit portions 29 are provided between and in axial alinement with said cylindrical conduit portions 28, said Venturilike conduit portions 29 having enlarged ends in unobstructed communication with said cylindrical conduit portions 28 and being contracted between their ends. Tubular means, in the form of a sleeve 21, snugly surrounds the cylindrical conduit portions 28 and co-acts with the contracted portions of the Venturi-like conduit portions 29, in forming pockets 30. The conduit portions 29 are provided between their ends with auxiliary portage 32 placing their interiors in communications with the pockets 3|). Perforations 2l) are formed in the sleeve 21, placing the pockets 3D in communication with the atmosphere.

The conduit in Fig. 3 is formed from a plurality of short tubes 33 having contracted ends 34 disposed toward the outlet end of the muiller, and a plurality of additional short tubes 35 abutting the tubes 33 and having reduced ends 36 disposed toward the intake end of the muler, the tube ends 34 being received within and spaced from the tube ends 3B to provide the Venturi-like portions 29 and the annular ports 32.

The sleeve 21 is preferably formed from sections 31 crimped or otherwise secured together at 38, said' sections having inwardly pressed ridges 39 abutting the tubes 33 and 35 at the juncture of their reduced ends with the larger portions of the tubes, thereby holding the latter tightly in position. The rst tube 33 is preferably provided with a lateral ilange 40 lying against a similar flange 4| on the rst sleeve section 31, these anges being secured together by crimping a portion 42 of the exhaust pipe 43, around them.

The structure illustrated in Fig. 3 functions in the same manner as that disclosed in Fig. 1.

The nozzlt -like throats 34 of Venturi-like portions 29 are structural and do not materially affect the pressure recovery ratio, inasmuch as the diverging discharge tubes 35 streamline the passage and reduce turbulence.

In Fig. 4, the muffler embodies a plurality of 'short axially alined tubes 44 each having two cylindrical end portions 45 and 46, a perforated step portion 41 at the inner extremity of the end portion 45, the perforations of said step portion being shown at 53, and a restricted portion 48 from said step portion 41 to the end portion 46. These tubes 44 are disposed in abutting end-to-end relation, and a plurality oi' additional short tubes 49 are snugly tted and secured inthe adjacent ends of said tubes 44. Each of the tubes 49 is provided with a contracted end 50 extending within the perforated step portion 41 and one end of the restricted portion 48 and spaced from the latter'. The cylindrical portions of the tubes 49 provide longitudinally spaced cylindrical conduit portions 2B* and the tube portions 48 and 50 co-act in forming axially alined Venturi-like conduit portions 29 between said cylindrical conduit portions 28X. The steps 41 constitute tubular means sur rounding the parts 50 of the Venturi-like portions 29X, said tubular means co-acting with said parts 5|) in forming annular pockets 5|. These parts 50 are spaced from the tube portions 48 to form annular auxiliary portage 52 from the interiors of the Venturi-like conduit portions 29 into the pockets 5|, and perforations 53 in the annular means 41 place said pockets in communication with the atmosphere.

Moreover, this structure functions in the same way as above described.

A substantially ilat, transversely rectangular muiiler is shown in Fig. 5, embodying a two-section sleeve 54 and two bent metal strips 55 secured within said sleeve. These strips are bent to provide airioils 56 spaced apart by straight strip portions 51, providing the conduit with alternate swells and restrictions and being hence the equivalent of a series of Venturi tubes. airfoils 56 co-act with the sleeve 54 in providing pockets 58 into which gas from the high pressure wave peak may iiow through the auxiliary ports 59 and from which it may discharge through the openings 6|) or into which air may dow through openings 6D and from which it may be drawn into the conduit through said auxiliary ports 59.

in Fig. 7, the construction is very similar' to that illustrated in Fig. 3, the alternate restrictions and swells in the diameter oi the gas conduit being provided by abutting tubes 33' and 35 having contracted ends 34 and 36 respec- 'tively which are spaced apart longitudinally of ably secured together at 38. When a tail-pipe is used as illustrated, the auxiliary gas discharge is more continuous depending upon the amount of restriction offered.

The structure shown in Figs. 8 to 1l is very similar to that shown in Figs. l and 2, the conduit being composed of Venturi tubes 22 spaced apart by spacing tubes 2|. The abutting tubes are snugly tted and held within a tapered sleeve 23 which coeacts with the restrictions of the conduit in providing gas conducting pockets 24. Gas conducting slots 25 formed in the Venturi tubes 22', lead to the pockets 24', and openings 26 in the sleeve 23', lead from said pockets. By preference, the slots or the like 25 increase gradually in width toward the discharge end of the muffler, and the diameters of the openings 26 increase gradually toward said muiiler end. Beyond the last spacing sleeve 2|', the sleeve 23 is preferably contracted as shown and provided with gas discharge perforations 6|. pered form shown, the auxiliary gas discharge is increased especially at the larger end of the mufliler-the amount depending upon the rate of taler and the degree of restriction at the smaller en The i In the ta- In Fig. 12, the assemblage 62 is practically identical with that shown in Fig. 8, but shorter, said assemblage being received in the larger end ofa tapered sleeve 63 and being iinwardly spaced from said sleeve. The portion of the sleeve 63 between the assemblage 62 and the delivery end 64 of sa'd sleeve, is occupied by Venturi tubes 22a and spacing tubes Zla providing alternate swells and restrictions, The restrictions cri-act with the sleeve 63 in providing pockets 24a having perforations 25n and 26a, gas-receiving pockets 26a to which perforations 25a extend and from wh'ch additional perforations 2lia lead to the exterior of the sleeve. The similarity of the assemblage G2 to the construction shown in Figs. 1 and 8, will be obvious, and the existing analogy between the structure 2| a, 22a, etc. and Figs. 1 and 8, will also be clear.

The structure of Fig. 12 provides a two-stage muffler which is well adapted to unusually noisy engines or to installations requiring unusual quieting of the exhaust gases.

In Fig. 13, an assemblage G5 constructed in the manner shown in Fig. 4, is centrally secured .in a longitudinally tapered jacket sleeve 66, said sleeve 66 having a dome-like front end 61 provided with air inlets 58 and being provided at longitudinally spacedV points with inwardly stamped portions providing gas outlets 69. stream-line type of this form of muiiler and the fact that the rush of air around the same will assist in causing discharge of exhaust gases, readily adapt it for use on aircraft.

In Figs. 14 and 15, an assemblage 1|] constructed as illustrated in Fig. 3;' extends longitud'nally within a transversely-stream-lined jacket sleeve 1l which is closed atl both of its ends and provided with gasescape slots 12 (or if desired, with series of perforations) The slots or the like "l2 are so located that the rush of air against the sleeve 'H in the direction of the arrows 13, causes the creation of outward suction through said slots or the like, assisting in Withdrawing the gases from the muliier. The gas inlet Hl extends into the conduit through one side of the jacket sleeve 1I and the tail end of the assemblage 1B is preferably reduced as de- Aassemblage T6 is provided with annular baffles T9 between its gas-conducting openings 80, said baiiies inclining toward the jacket sleeve 11 and termnating in spaced relation with the latter.

' From the openings 80 toward the intake end of the muffler, exhaust gases discharge into the space between the sleeve-s 18 and 11. At the delivery end of the muliler, the Venturi throats are of less diameter than those at the intake end so that the gases previously discharged into said space are returned into the conduit by suction and discharged through the final outlet 8|. From the openings 80 toward the intake end of the muffler, exhaust gases discharge into the space between the sleeves 18 and 1l, but toward the delivery end of the muffler, the pressure of the gases within the conduit becomes so reduced, that the gases previously discharged into said space, are returned into the conduit by suction and discharged through the nal outlet 8|.

It will be seen from the foregoing that most forms of the invention comprise a straight tubular gas conduit having longitudinally spaced axi- The ally alined cylindrical portions which enlarge the diameter of the conduit both internally and externally, said conduit also having longitudinally spaced axially alined Venturi-like portions between sa'd cylindrical portions which decrease i the diameter of the conduit both externally and internally between said enlargements, said Venturi-Lke portions being in unobstructed communication with said cylindrical portions, each of said Venturi-like portions having a restricted lo substantially annular (either continuous or a ring of perforatons) auxiliary port from the interior to the exterior of its contractedintermediate portion, and tubular means surrounding at least parts of said Venturi-like conduit porl5 tions and spaced radially therefrom to provide annular pockets, the peripheral walls of said pockets having openings. Mufflers so constructed, well attain the ends for which they are designed and lend themselves admirably to use either with 20 or Without an enveloping .jacket sleeve or the like.

It may be added that the pressure head at the peaks of the exhaust waves, is amply sufficient to overcome any vacuum that might otherwise exist at the Venturi throats. The wave phenomenon is due to the inertia of the gases and cannot be smoothed out before the gases enter the muflier except with a very long exhaust pipe or exorbitantly large manifold. A pressure gauge in the exhaust line (due to lag) fails to show the true state of affairs. The best it will show is the mean pressure. The peaks of the waves possess comparat vely high pressure.

While various forms of construction have been shown for illustrative purposes, variations'may of course be made within the scope of the invention as claimed.

1. In a muffler, an'assemblage comprising a4() gas conduit having a plurality of axlally alined Venturi-like formations providing alternate swells and restrictions, and ports from said restrictions to the exterior of the conduit, and means co-acting with at least portions of said restrictions in providing pockets at the exterior of said restrictions, said means having openings from said pockets to its exterior; a sleeve into one end of wh'ch said assemblage extends, saidl sleeve being spaced from the periphery of said assemblage and extending longitudinally beyond the same; and a second gas conduit snugly secured in the portion of said sleeve beyond said assemblage and composed of a plurality of axially alined Venturilike formations providing additional alternate swells and restrictions, the restricted portions of said second conduit co-acting with said sleeve in forming pockets and having ports into said pockets, said sleeve having openings from said pockets to its exterior.

2. A muffler comprising a tapered gas conduit having a plurality of axially alined Venturi-like formations providing it with alternate swells and restrictions, said formations having ports from the interiors to the exteriors of said restrictions, a tapered sleeve in which said conduit is snugly fitted and secured, said sleeve co-acting with the exteriors of said restrictions in providing annular pockets and having additional openings from said pockets to theexterior of the sleeve, said sleeve having a gas inlet at its larger end and a gas outlet at its smaller end; a second tapered sleeve into whose larger end the rst mentioned sleeve extends, said second tapered sleeve being tapered in the same direction as said rst mentioned sleeve, extending beyond the latter and being spaced from the periphery thereof; and a second tapered gas conduit having a second plurality of axially alined Venturi-like formations providing additional alternate swells and restrictions, said second conduit being snugly tted and secured in the portion of said second sleeve between the first mentioned conduit and the smaller end of said second sleeve; said portion of said second sleeve co-acting with the exteriors of said additional contractions in providing additional pockets and having openings from said additional pockets to the exterior of said second sleeve, said second sleeve being provided at its smaller end with a gas outlet,

3. A muffler comprising a gas conduit composed of a plurality of axially alined tubular portions, each of which is provided with a swelled intermediate portion and contracted ends, said tubular portions being disposed in end-to-end relation and having their ends spaced apart to provide ports, and a sleeve in which said tubular portions are snugly fitted and secured, said sleeve co-acting with the exteriors of said contracted ends in forming pockets and having openings from said pockets to the exterior of the sleeve.

4. A muil-ler comprising a gas conduit having a plurality of axially alined Venturi-like formations providing it with alternate swells and restrictions, said restrictions having ports from their interiors to their exteriors; a sleeve in which said conduit is snugly tted and secured, said sleeve co-acting with the exteriors of said restrictions in providing pockets and having openings from said pockets to its exterior; an outer imperforate jacket sleeve surrounding and spaced from the rst mentioned sleeve and having closed ends, and annular gas baiiles projecting from said first mentioned sleeve toward said jacket sleeve but spaced from the latter.

5. A muffler comprising a conduit composed of a plurality of short axially alined tubes disposed end to end, each of said tubes having cylindrical end portions, a perforated portion at the inner extremity of one of said cylindrical end portions, and a restricted portion extending from said perforatcd portion to the other of said 'cylindrical end portions; and additional short tubes snugly fitted and secured in the adjacent cylindrical end portions of the lirst mentioned short tubes, said v additional short tubes having contracted ends extending within said perforated portions into.

and restrictions, providing annular pockets with which the perforations communicate, and ports from the interior of the conduit into said pockets.

6. In a muler, an assemblage comprising a conduit having a plurality of axially alined Venturi-like formations providing alternate swells and restrictions, and ports from the interiors to the exteriors of said restrictions; and means at the exterior of the conduit co-acting at least with portions of said restrictions in forming pockets with which said ports communicate, said means having additional openings from said pockets to the exterior of the latter; said conduit having a gas inlet at one end and a gas outlet at its other end; and a jacket sleeve surrounding the above-dened assemblage, said jacket sleeve having a dome-like front end provided with air admission openings, being tapered rearwardly and having longitudinally spaced air and gas discharge openings.

y --7. A mufller comprising an elongated cylindrical casing having longitudinally spaced groups of periorations, short cylindrical tube members secured in and in contact with said casing, said short cylindrical tube members being located between said groups of perforations, and Venturilike tubes extending between said short cylindrical tube members, each of said Venutri-like tubes having both of its ends enlarged and disposed directly at and in gas-tight relation with the adjacent ends ol the two adjacent cylindrical tube members, said Venturi-like tubes having passages from the interiors to the exteriors of their contracted intermediate portions, the per` forations of said cylindrical casing being in portions thereo which do not contact with said Venturi-like tubes.

8. A muiiler comprising longitudinally spaced axially alined cylindrical conduit portions and Venturi-like conduit portions between and axially alined with said cylindrical conduit portions, said Venturi-like conduit portions having enlarged ends in unobstructed communication with said cylindrical conduit portions, being contracted both internally and externally between their ends and being provided in their contracted portions with openings, and tubular means surrounding at least parts of said Venturi-like conduit portions and spaced radially therefrom to provide annular pockets, said pockets being placed in communication with the interiors of said Venturilike conduit portions by means of s'aid openings, the peripheral walls of said pockets having openings. 

